Validate document lines on the server and recompute their totals, store notes with quotes/markup/emoji (utf8mb4, idempotent escaping, decode in form fields), exclude transfers from company-wide stock in/out, count revenue from confirmed orders only, one low-stock rule everywhere, list unapproved lots, natural bin sort, stable order/PO sort, status tiles that add up.
Store the put-away location on return lines (new td_return_item columns, needs setup.php), split auto credit notes into net and VAT with the parent's department, drop the write to a td_quotation column that does not exist, and have the demo seed confirm its customer return.
Thanakorn